Heretofore it has been known to provide easy open can ends with pull tabs which remain affixed to the can. At the present time, most easy open can ends are of the so-called "push in" type where a portion of the can end is pushed downwardly into the liquid contents of the can. The U.S. Pat. Nos. issued to Cudzik, namely 3,967,750; 3,967,752 and 3,967,753 are illustrative of this type of can end construction. The principal objection to this type is a lack of cleanliness in that the portion of the can end that is pushed into the liquid contents may contain dust, dirt or other contaminants that are directly introduced into the beverage.
A second general type of problem illustrated in much of the prior art patents is the failure to maintain control of the final position of the tear strip and pull tab. In many of these patents, the tear strip is loosely pulled back and the pull tab and tear strip are simply draped over the sides of the can. Thus the user who drinks from the dam is exposed to the raw edges of the tear strip.
Still another existing problem is the jagged sawtooth edge found on existing score line patterns. This problem is not readily observable although one can feel that a problem exists. This problem exists because of the tendency for a tear to follow first one side of the bottom of a score line and then to switch to the other side. This zigzag rupture pattern produces sharp sawtooth like edges at the bottom of the score pattern which will quite easily cut the user's tongue or lips.
Finally, the prior art easy open can ends have been plagued almost from the start by leading rivets caused by cracking in the region of the rivet because of the extremely severe stresses encountered in forming a rivet from a single thickness of metal.